package AtomicXXX;

import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.LongAdder;

public class T02_AtomicVsSyncVsLongAdder {

    static long count2 = 0l;
    static AtomicLong count1 = new AtomicLong(0l);
    static LongAdder count3 = new LongAdder();

    public static void main(String[] args) throws Exception {
        Thread[] threads = new Thread[1000];
        for(int i = 0; i < threads.length; i++){
            threads[i] = new Thread(() ->{
                for(int k = 0; k < 100000; k++) count1.incrementAndGet();
            });
        }

        long start = System.currentTimeMillis();

        for(Thread t : threads) t.start();
        for(Thread t : threads) t.join();

        long end = System.currentTimeMillis();

        System.out.println("Atomic: " + count1.get() + " time:" + (end-start));

        //---------------------------------------------------------//
        Object lock = new Object();
        for(int i = 0; i < threads.length; i++){
            threads[i] = new Thread(() ->{
                for(int k = 0; k < 100000; k++){
                    synchronized (lock){
                        count2++;
                    }
                }
            });
        }

        start = System.currentTimeMillis();

        for(Thread t : threads) t.start();
        for(Thread t : threads) t.join();

        end = System.currentTimeMillis();

        System.out.println("Sync: " + count2 + " time:" + (end-start));

        //---------------------------------------------------------//
        for(int i = 0; i < threads.length; i++){
            threads[i] = new Thread(() ->{
                for(int k = 0; k < 100000; k++) count3.increment();
            });
        }

        start = System.currentTimeMillis();

        for(Thread t : threads) t.start();
        for(Thread t : threads) t.join();

        end = System.currentTimeMillis();

        System.out.println("LongAdder: " + count3 + " time:" + (end-start));

    }
}
//为什么atomic要比sync快 因为atomic用来CAS操作
//LongAdder内保用了分段锁,在线程数很多的情况下是很有优势的